Wool scouring process

ABSTRACT

THE INVENTION RELATES TO A PROCESS OF SCOURING WOOL USING A HYDROPHILIC SOLVENT OR MIXTURE OF SOLVENTS AFTER THE RAW WOOL HAS BEEN FIRST WASHED WITH WATER AT A TEMPERATURE BELOW THE TEMPERATURE AT WHICH WOOL WAX MELTS ANE PREFERABLY AT OR BELOW AMBIENT TEMPERATURE. THE SOLVENT/WATER RATION IN THE SOLVENT STAGE INTO WHICH THE WATER WET WOOL PASSES IN CONTROLLED TO ENSURE THAT SUBSTANTIALLY ALL THE WOOL WAX DISSOLVED IN THE SOLVENT REMAINS IN SOLUTION.

A08 17 1971 WA. COUCHE mm.

woon ooumwa moms@ Film Aug.. 8, 196

l Wafer Was/why fec/of? 1"" ATTORNEYS 'United States Patent O 3,600,124 WOOL SCOURING PROCESS Raymond Arthur Couche, 168 Adelaide Terrace, Perth, Western Australia, Australia Filed Aug. 8, 1968, Ser. No. 751,250 Int. Cl. D01c 3/00; C11b 11/00 U.S. Cl. 8-139.1 12 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a process of scouring wool using a hydrophilic solvent or mixture of solvents after the raw wool has been first washed with water at a temperature below the temperature at which wool wax melts and preferably at or below ambient temperature. The solvent/water ratio in the solvent stage into which the water wet wool passes is controlled to ensure that substantially all the wool Wax dissolved in the solvent remains in solution.

This invention relates to an improved wool scouring process and is a development of the invention the subject of U.S. Pat. No. 3,441,368.

The aforesaid previous invention is directed to a process for scouring wool which comprises washing the wool with water to remove suint and then passing the washed wool through a series of stages in which it is washed with an organic solvent or mixture of organic solvents in which wool wax is soluble, which is miscible with water and has la boiling point or boiling range below the boiling point of water, the solvent passing from one stage to another countercurrent to the wool, the solvent from at least one of the stages being treated where necessary to remove substantially all the wool wax dissolved therein before being fed to the next stage.

As a result of experience with the operation of the aforesaid process of the previous invention it has been found that it is not essential that the wool wax be separated from the solvent between stages.

Thus in its broadest form the present invention resides in a process for scouring wool which comprises passing the wool through a series of stages in which it is washed with an organic solvent or mixture of solvents in which wool wax is soluble and which is miscible with water characterised in that the Wool is washed with water before the solvent washing procedure and in that the solvent passing from one stage to another is not treated to remove the wool grease dissolved therein.

More particularly the present invention resides in a process for scouring wool which comprises washing the wool with water to remove suint and then passing the Washed wool through a series of stages in which it is washed with yan organic solvent or mixture of organic solvents in which wool wax is soluble, which is miscible with water and has a boiling point or boiling range below the boiling point of water, the solvent passing from one stage -to another countercurrent to the wool, the solvent/ water ratio in the solvent stage into which the Water wet Wool passes being controlled to ensure that substantially all the wool wax dissolved in said solvent remains in solution.

Throughout this specification the wool will be described as passing from the first stage to the second stage and then to the third stage and so on while the water or solvent will be described as passing from the third stage to the second stage and then to the first stage. In other words the Wool will be described as moving forward while the water or the solvent will .be describedY as moving backward or rearward.

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lt is preferable that the water washing be carried out at or below ambient temperature i.e. approximately 20 C. It is desirable that the water washing be carried out at a temperature below the temperature at which the wool wax melts to eliminate the possibility of suint scouring. The solvent washing is carried out at an elevated temperature within the range of 45 C. to the boiling point of the solvent at which temperature dissolution of the wool wax is rapid and the wool substantially unaffected. It is also preferable that the last stage i.e. the stage at which fresh solvent is introduced to the system and from which the wool leaves the system be carried out at or below ambient temperature.

The washing of the wool with cold water for removal of suint may be effected by passing the Wool through a cold water bath or by spraying the wool with cold water and then removing the excess water such as by squeezing or it may comprise one or more such washes preferably with the cold Water moving from one bath to another countercurrent to the passage of the wool in order to obtain maximum removal of suint with a minimum quantity of water to produce a suint solution of reasonably high concentration which facilitates recovery of potassium salts from the suint solution if this is so desired. The wool thus leaves the water washing section in a squeezed or wet condition still containing substantially all of the wool wax and most of the impurities and a small proportion of the suint. In order to ensure that the moisture content of the wool leaving the water washing section and entering the solventwashing section is at a minimum the wool is passed through squeeze rollers or through a suction drum or is subjected to some other mechanical treatment for the removal of water therefrom. It is desirable that the moisture content of the wool leaving the water washing be reduced to a minimum before it is contacted by the solvent.

Each of the solvent washing stages comprises a vessel filled with a solvent, means being provided to pass the wool through the solvent and then substantially removing the excess solvent such as by squeezing before passing it to the next bath, the excess solvent removed by the squeezing flowing back into the vessel from which the wool has been withdrawn. Preferably the solvent in each stage is circulated from or near the bottom of the vessel and through a filter or an alternative cleaning device. to remove solid impurities and the clean solvent returned to the vessel at or near the top thereof and preferably arranged to Iflow over the wool closest to the outlet from the vessel. Each of the solvent stages except the last (i.e. the last stage through which the wool passes) is provided with thermostatically controlled heating means.

The quantity of solvent in the first solvent stage i.e. the stage in which the water wet wool enters the solvent washing section is regulated to ensure that the wool wax dissolved in the solvent remains in solution and is not precipitated by the water. The water is displaced from the wool by the solvent thereby producing an aqueous solution in which the wool wax is less soluble than in the pure solvent. Therefore in order to prevent separation of the Wool waX from the solvent when it takes up the water there must be suicent solvent present. In most cases separation of the wool wax from the solvent will be prevented by maintaining the solvent/water ratio in this stage at more than 9:1 [by volume.

In order to obtain satisfactory scouring it has been found that a three stage water washing section and a four stage solvent Washing section is suilicient.

In the process of the aforesaid earlier application care has been taken to prevent unnecessary movement of the wool with a view to eliminating or substantially reducing felting and tangling. It has been found that with the process of the present invention such a requirement is not necessary. In both the water washing and solvent washing sections of the present process the wool can be allowed to flow freely without any felting or tangling occurring. This ensures that the dirt can be readily washed from. between the fibres, Also it enables conventional detergent scouring equipment comprising bowls fitted with rakes to be adapted for the process of the present invention. For the water washing section substantially no modification of the bowls is necessary while for the solvent washing section it would be necessary to fit vapor tight hoods or other means to each of the bowls to prevent evaporation and escape of solvent. If desired the wool may be carried through successive stages on a travelling belt which passes from one stage to another or each stage may be equipped with its own belt, the wool being passed from one belt to another as it passes from stage to stage. 1n some circumstances it may be desirable to constrain the wool against movement as in the aforesaidearlier application.

Solvents suitable for the purpose of the present invention include acetone, isopropyl alcohol or a mixture of ethyl alcohol, ethyl acetate and acetone in the ratio of 1:1:1 or a mixture of ethyl alcohol, ethyl acetate and isopropyl ether in the ratio of 4:211. Hydrocarbon solvents are not suitable for -the purposes of the present invention because they are not miscible with water. It is essential that the solvent be miscible with water so that a substantial proportion of the water which remains in the wool after it leaves the Water washing section will be removed in the first solvent stage.

The various features of the present invention will be better understood from the following description of the operation of a pilot plant in accordance with the process which is illustrated in the accompanying drawing which is a flow sheet.

EQUIPMENT The pilot plant consisted of seven extraction vessels V each substantially rectangular in plan and end elevation and substantially V-shaped in side elevation. Each of the extraction vessels corresponds to one of the stages shown in the flow sheet and was provided with perforated baskets in which the wool could be placed in a free float condition. Each vessel was provided with means for raking the wool in the free fioat condition and with hand operated rollers R for pressing the wool before it proceeded to the next stage.

Flow of water and solvent through the vessels was controlled by owmeters and the temperature in each vessel indicated by a vapor pressure dial thermometer. The solvent and water used in the vessels was circulated with centrifugal pumps. Dirt was removed from the hot grease laden solvent with 2" fiuid cyclones and a pilot size clarifying centrifuge C.

The solvent recovery unit was a fractionating or distillation column D of 11" inside diameter and 14 feet high packed with l" ceramic Raschig rings. The column was automatically controlled using a differential vapor pressure cell with the sensing element approximately 1/3 from the column ibase. A Water tube condenser E recovered the solvent returning it to a head tank F. Reflux was provided to the head of the column from a constant head distillate unit, the surplus gravitating to the head tank. A vapor connection from the top of the condenser to the common vent system eliminated pressure surges in the distillation system.

A single pass dryer G was constructed using a stainless steel chain mesh belt and circulating air through a steam heating coil to the dryer from which it was drawn by a centrifugal fan to pass through a Raschig ring packed absorption column H before returning to the heater and dryer.

4 PROCEDURE Wool was loaded in the perforated baskets at a rate of approximately 10 pounds of raw wool per hour and the wool in a free fioat condition subjected to a gentle raking action while in each stage. The wool before being passed from one stage to the next was passed through the manually operated rollers to remove as much liquid as possible from the wool. This pressing operation allowed liquid equal to about 60-80 percent of the dry weight of wool to pass forward to the succeeding stage and into the dryer. The retention time in each stage was of the order of 30 seconds. All the water washing (three stages) was carried out at ambient temperature. The first three solvent washing stages were carried out at 50 C.i2 C. while the fourth and final solvent stage was carried out at ambient temperature. The wool from the final washing stage was passed through the dryer. The water rate varied from 0.5 to 2 litres per minute (1.1 to 4.4 pounds/ minute) depending on the type of wool. For clean wool such as fieece and lambs the rate was at the lower end while for the darker wools such as locks and crutching a higher water fiow was necessary. The solvent How rate was between 1.0 and 1.5 litres per minute (l.75-2.6 pounds/minute) the actual rate depending on the type of wool and the quantity of water carried by the wool into the first solvent stage. Throughout the pilot plant operation the solvent flow was adjusted to maintain a water content of 8-10 percent by weight in the first solvent stage. In general the solvent ow should be maintained at a high enough rate to ensure that the water content of the wood entering the first solvent stage does not cause precipitation of the wool wax dissolved in the solvent but maintains the solvent/water ratio of the liquor so that the liquor remains at or near saturation with respect to wool wax. For this purpose it is desirable that the solvent ow rate and/or the water carried forward with the wool into the first solvent stage should not produce a moisture content above 15% by weight and preferably not above 10% weight, the exact moisture content permissible depending on the quantity of wool wax in the raw wool. If desired the dirtier wools such as locks and crutchings may be given a preliminary soaking in water for between 45 and 60 minutes.

The solvent passing from the first solvent stage was passed to the distillation unit after being passed through a clarifying centrifuge to remove suspended dirt. The aqueous emulsion passing out of the distillation column was cracked with sulphuric acid and the wool wax recovered by melting the flocculated grease particles and separating the solidified grease layer from the aqueous efiluent after cooling.

RESULTS All wool processed was clean, fibres unaffected, of good bloom and tensile strength. The feel was soft and appearance excellent. The freedom from tangling indicated the possibility of the separation of most vegetable faults, residual dags and dirty tips when present during carding and this possibility was subsequently confirmed by carding samples of processed wool.

The yields of clean wool were as follows:

Percent at 16% regain Fleece-60% yield 66 Lambs-61.7% yield 66 Locks-45.1% yield 49 Crutchings-55.3% yield 60 The moisture content of the processed wool after reaching equilibrium and the residual grease and suint contents of moisture free samples of the processed wools were as follows:

Norm-Moisture content was determined by drying to a constant weight at 102 C.: residual grease was determined by Soxhlet extraction with hexane. A weighed quantity of dry wool was introduced to the Soxhlet thimble and extracted for 24 hours. The grease was determined by evaporation of the solvent and direct weighing of the grease residue; residual suint was determined by water washing a weighed quantity of dry wool which was gently squeezed in a large excess of clean cold water and then squeezed free of excess water. The washing was repeated with three lots of fresh water, the wool dried to a constant weight and the loss of weight recorded as suint. This technique measured all loss of weight as suint and consequently includes all retained dirt and short fibre particles which were washed out of the sample.

I claim:

1. A process for scouring wool which comprises washing the wool with water to remove suint and then passing the washed wool through a series of stages in which it is washed with an organic solvent material in which wool wax is soluble, which is miscible with water and has a boiling point or boiling range below the boiling point of water, passing the solvent from one stage to another countercurrent to the wool, controlling the solvent water ratio in the solvent stage into which the water wet wool passes to ensure that substantially all the wool wax dissolved in said solvent remains in solution.

2. A process as claimed in claim 1 wherein the water washing is carried out at a temperature not exceeding ambient temperature.

3. A process as claimed in claim 1 wherein the solvent washing is carried out at a temperature within the range of 45 C. to the boiling point of the solvent.

4. A process as claimed in claim 1 wherein the wool is subjected to mechanical treatment such as squeezing or suction to remove liquid therefrom after leaving each of the water washing or solvent washing stages and before being passed to the succeeding stage.

5. A process as claimed in claim 1 wherein the solvent is acetone.

6. A process as claimed in claim 1 wherein moisture content of the rst solvent stage is maintained below 15% by weight.

7. A process as claimed in claim 1 wherein the moisture content of the rst solvent stage is maintained -below 10% by weight.

8. A process as claimed in claim 1 wherein the wool in each stage is in a free oat condition and is subjected to a raking action.

9. A process as claimed in claim 1, wherein the solvent is isopropyl alcohol.

10. A process as claimed in claim 1, wherein the solvent is a mixture of ethyl alcohol, ethyl acetate, and acetone inthe ratio 1:1:1.

11. A process as claimed in claim 1, wherein the solvent is a mixture of ethyl alcohol, ethyl acetate, and isopropyl ether in the ratio 4:2: 1.

12. A process for scouring wool which comprises washing the wool with water at a temperature below the melting point of wool wax to remove suint, passing the washed wool through a series of stages in which it is washed with an organic solvent material in which wool wax is soluble, which is miscible with water and has a boiling point or boiling range below the boiling point of water, the solvent passing from one stage to another counter-current to the wool, controlling the solvent water ratio in the solvent stage into which the water wet wool passes so that the moisture content is less than 15% by weight and said wool being subjected to mechanical treatment such as squeezing or suction to remove liquid therefrom after leaving each of the water washing or solvent washing stages and before being passed to the succeeding stage.

References Cited UNITED STATES PATENTS 1,521,624 1/1925 Herzog 8-139.1 3,210,148 10/1965 Delforge 8-139.1 3,441,368 4/1969 Couche 8-139X MAYER WEINBLATT, Primary Examiner U.S. Cl. X.R. 

